Insect floral visitors of Solanum melongena var. Black Beauty (Solanaceae) and impact of the foraging activities on the pollination, fruit and seed yields at Dourga (Far North, Cameroon)

At Dourga, from july to december 2022 and june to november 2023, the investigations were made on Solanum melongena (Solanaceae) to determine the activities of the insects, the floral products required, the relative frequency and to evaluate the impact of these insects on the fruit and seed yields of this plant. For that purpose, two treatments were formed each year starting from the marking of 240 floral buttons by the absence or the presence of protection of insects visit on flowers. The observations were made on the flowers of S. melongena in free pollination from 12th to 20th October 2022 and from 22th September to 1st October 2023. The insects harvested the eggplant flowers between 6 am and 3 pm, with the peak of activity situated between 8-9 am. They collected pollen exclusively on the flowers of S. melongena. 3153 visits of 13 insects’ species were inventoried and belong to two orders (Hymenoptera, Diptera) and seven families. Seladonia sp. was the most frequent species with 38.98% of visits, followed by Amegilla calens (14.05%) and Apis mellifera (12.37%). The comparison of the yields of the treatments showed that the flowering insects increased the fruiting rate, the number of seeds per fruit and the percentage of normal seeds of 35.65%, 12.67% and 11.72% respectively. This study provided some knowledge on the diversity of the pollinating insects of this plant, which can be exploited to improve the fruiting production. Thus, for the period of flowering of eggplant, the treatments with chemical pesticides are to be avoided to be able to benefit from the service of pollination ensured by the flowering insects.